Data_Sheet_2_New miRNA Signature Heralds Human NK Cell Subsets at Different Maturation Steps: Involvement of miR-146a-5p in the Regulation of KIR Expression.ZIP

Natural killer cells are cytotoxic innate lymphoid cells that play an important role for early host defenses against infectious pathogens and surveillance against tumor. In humans, NK cells may be divided in various subsets on the basis of the relative CD56 expression and of the low-affinity FcγRIIIA CD16. In particular, the two main NK cell subsets are represented by the CD56bright/CD16−/dim and the CD56dim/CD16bright NK cells. Experimental evidences indicate that CD56bright and CD56dim NK cells represent different maturative stages of the NK cell developmental pathway. We identified multiple miRNAs differentially expressed in CD56bright/CD16− and CD56dim/CD16bright NK cells using both univariate and multivariate analyses. Among these, we found a few miRNAs with a consistent differential expression in the two NK cell subsets, and with an intermediate expression in the CD56bright/CD16dim NK cell subset, representing a transitional step of maturation of NK cells. These analyses allowed us to establish the existence of a miRNA signature able to efficiently discriminate the two main NK cell subsets regardless of their surface phenotype. In addition, by analyzing the putative targets of representative miRNAs we show that hsa-miR-146a-5p, may be involved in the regulation of killer Ig-like receptor (KIR) expression. These results contribute to a better understanding of the physiologic significance of miRNAs in the regulation of the development/function of human NK cells. Moreover, our results suggest that hsa-miR-146a-5p targeting, resulting in KIR down-regulation, may be exploited to generate/increment the effect of NK KIR-mismatching against HLA-class I+ tumor cells and thus improve the NK-mediated anti-tumor activity.

自然杀伤细胞 (Natural killer cells) 是一类细胞毒性固有淋巴细胞，在宿主早期抵御感染性病原体的免疫防御以及肿瘤监视过程中发挥重要作用。在人类机体中，可根据CD56分子的相对表达水平以及低亲和力FcγRIIIA（CD16）的表达特征，将NK细胞划分为多个亚群。其中两大核心NK细胞亚群为CD56bright/CD16−/dim与CD56dim/CD16bright NK细胞。实验证据表明，CD56bright与CD56dim NK细胞分别代表NK细胞发育通路中的不同成熟阶段。本研究通过单变量分析与多变量分析，鉴定出在CD56bright/CD16−与CD56dim/CD16bright NK细胞中差异表达的多种微小RNA (miRNAs)。其中，部分微小RNA在两大NK细胞亚群中呈现稳定的差异表达模式，且在CD56bright/CD16dim NK细胞亚群中呈中间表达水平，该亚群对应NK细胞成熟的过渡阶段。上述分析使我们得以确立一套能够有效区分两大主要NK细胞亚群的微小RNA特征谱，且该特征谱不受细胞表面表型的影响。此外，通过对代表性微小RNA的潜在靶基因进行分析，我们发现hsa-miR-146a-5p可能参与调控杀伤细胞免疫球蛋白样受体 (KIR) 的表达。本研究结果有助于更深入地理解微小RNA在调控人类NK细胞发育与功能过程中的生理学意义。此外，我们的研究结果提示，通过靶向调控hsa-miR-146a-5p以实现KIR的下调，可用于增强NK细胞针对人类白细胞抗原I类阳性（HLA-I类+）肿瘤细胞的KIR错配杀伤效应，进而提升NK细胞介导的抗肿瘤活性。